Soot blaster

Soot blaster, comprising:

• a lance tube for emission of high-velocity fluid jets;
• rotating means for rotating said lance tube;
• drive means for linearly advancing and retracting said lance tube;
• at least one coupling interposed between the lance tube and one of said means;
• a limit switch at a forward end of the lance tube path;
• a time-delay relay controlled by said limit switch and connected with said coupling;
• said coupling being interposed between said drive means and said lance tube;
• and a single electric motor for operating said drive means;
• said coupling being disengaged for a predetermined time interval set by said time-delay relay;
• said single motor generating two components of motion comprising linear and rotary motions of the lance tube, said motor continuing to generate one component of motion when the other component of motion is arrested, said limit switch releasing the arrested component of motion by applying a signal through said relay to reverse the motor and thereby retract the lance tube after position of said jets has been changed, so that said coupling is temporarily disengaged and the jets define a different path, every blasting process being initiated at a different jet position.